Telephone-exchange system



(N0M0de1.)-

J. I. SABIN 85 W. HAMPTON.

TELEPHONE EXGHANGE SYSTEM.

Patented A l 17, 1894.

alz n 17206227573". 01m [,5 ZZLKLTH 0-774 UNITED STATES PATENT OFFICE.

JOHN I. SABIN AND WILLIAM HAMPTON, OF sAN FRANCISCO, CALIFORNIA.

TELEPHONE-EXCHANGE SY ST EM.

SPECIFICATION forming part of Letters Patent No. 518,334, dated April17, 1894. Application filed April 13, 1893. Serial No. 4'70.2 9- (Nomodel-l .To all whom it may concern.-

Be it known that we, JOHN I. SABIN and WILLIAM HAMPTON, citizens of theUnited States, residing in the city and county of San Francisco, Stateof California, have invented certain new and useful Improvements inSystems for OperatingSubscribers Signaling and Clearing Indicators onMetallic Circuits, of which the following is a specification.

Our invention relates to telephone systems, and its object is to reduceand render more uniform the time required to secure connection and toprovide means, whereby signals for disconnection and for calling maybetransmitted to the central office with minimum exertion on behalf of thesubscriber.

Our invention in its preferred embodiment comprises a metallic circuittelephone line extending to a switch at the central office, or inmultiple systems to the switches upon the several boards. A pair ofcontact anvils are provided against which the line springs normallyrest, thecontact anvils being connected to a local circuit including theoperators cap telephone. A switch is provided at the subscribersstation, preferably operated by his telephone hook which is normallyopen, but which, when closed, connects the subscribers telephone set incircuit with the operators cap telephone.

It will be understood that inexchanges where a single operator cannotattend to all of the calls, each operator attends to'a definite numberof the subscribers of the exchange, both according to the multiple boardsystem and the divided board system. The contact anvils belonging to thespring jacks of all such subscribers are connected through the operatorscap telephone, so that any one of the subscribers so connected may cuthimself into circuit even though the operator be holding conversationwith another subscriber. The operator becomes trained in attending tothe various calls though several be calling for connection at the sametime. The subscribers when in conversation are connected by'a pair ofplugs provided with two strands, a tip and a sleeve strand. The linesprings normally in contact with the contact anvils are moved away fromthe same when the plug is inserted, theoperators cap telephone beingthereby cut out of circuit. The operators listening-in telephone, whenused, and the generator are adapted to be bridged between the cordstrands. Between the strands is provided a bridge connection containinga battery, and an indicator is provided therein or a pair of indicatorsare provided in the strands uponopposite sides of said bridge to serveas clearing-out indicators.

We will describe our invention more in detail in connection with theaccompanying drawings, in which- Figure 1 illustrates two subscribersmetallic circuits connected together for conversation. Fig. 2 shows amanner of connecting the operators local circuit in a multiple boardsystem connected according to the series switch plan.

In Fig. 1 we have illustrated the subscribers line extending to a singleboard at the central office, it being understood that our invention mayequally'be applied to multiple boards, as illustrated in Fig. 2, or byextending the lines to switches in multiple at the other boards,in whichcase it would be preferable to extend the operators local telephonecircuit through the several spring jacks so that a connection at anyboard would serve to cut the indicator from circuit.

The limbs a a of the metallic circuit ofsubscriber A are connected withthe line springs a a. Likewise, the limbs 19' b of the metallic circuitof subscriber B are connected with the line springs 19 17 The springs aa rest normally against contact anvils c c, which are connected with thelocal metallic circuit containing the operators cap telephone. Likewisethe springs b 6 rest normally against contact anvils 0 0 also connectedthrough the operators cap telephone. A switch c is provided, by means ofwhich the operator,-when she desires to remove the cap telephone, maycut the same from the circuit, and include therein the battery e and theoperators individual indicator e. When the battery and indicator arethus in circuit the subscriber, by removing his telephone from the hook,closes the battery circuit, and the indicator displays the visualsignal, thus informing the operator that a connection is desired. Shemay then replace the cap telephone and receive the order. When inconversation the subscribers are connected by a pair of plugs and adouble stranded cord. The plugs, when inserted in the spring jacks, movethe line springs away from their contact anvils, thereby cutting the captelephone out of circuit. The operators listening-in telephone set fisincluded in a bridge between the two strands of the cord, and a key f isprovided whereby the telephone may be bridged into circuit. The callinggenerator g is likewise includedin abridge between the strands, a pairof keys g 9 being provided whereby the calling currents may be sentthrough either plu A battery It and an indicator h are included in abridge between the two strands of the cord connector. So long as thetelephone at either subscribers station remains off the hook the circuitof battery It is closed through indicator h, but so soon as both hang uptheir telephones, the circuit of battery it is opened and the indicatorbeing no longer energized, indicates a desire for disconnection. Inorder that the circuit through said battery may be open except when thetelephone is off the hook, the bridge containing the bell may contain acondenser t'. Instead of a single clearing-out indicator h, a pair ofindicators 7L2 72. may be employed, as indicated in dotted lines, theindicator It being controlled by subscriber A, while indicator k iscontrolled by subscriber B.

It is evident that other forms of subscribers station apparatus may beemployed, the requisite being that the circuit remain closed at thesubscribers station while the subscriber is talking.

We will now describe briefly the several operations required to secureconnection between two subscribers. Subscriber A, wishing to talk withsubscriber B, removes his telephone and is immediately in circuit withthe operators cap telephone. The operator having received from thesubscriber the number of subscriber B, inserts plug on into the springjack of subscriber B and bridges her listening-in telephone set betweenthe cord strands. If B is busy through a connection at some other board,there will be a difference of potential between the line springs of thespring jack, and as the plug is inserted she will hear a click in hertelephone. If subscriber B be not busy, the operator inserts plug m inthe spring jack of subscriber A, and depresses ringing key 9 to send acalling current to subscriber B. Subscriber B having responded, she cutsout her telephone set and the subscribers are in connection. When theconversation is completed, the subscribers hang up their telephones,thus opening the circuits of the battery it through the indicator h,when one is used, or through indicators 71. h when two are used.

This application is one of a series of com currently pendingapplications Serial Nos. 464,509; 465,791; 490,950, and 499,954 and sofar as anything shown herein is claimed in anyof said applications, thisapplication is to be considered subsidiary thereto.

Having described our invention, what we claim, and desire to secure byLetters Patent, 1s-

1. The combination with a metallic circuit telephone line, extending tothe central station, of a metallic local circuit containing theoperators cap telephone normally in circuit with said line, and means atthe subscribers station for closing his telephone set in circuit withsaid cap telephone, substantially as described.

2. The combination with a metallic circuit telephone line extending tothe central station and normally open at the subscribers station, of ametallic local circuit containing the operators cap telephone normallyin cir' cuit with said line, and a switch at the sub scribers stationadapted to be actuated by the removal of the telephone from its hook toclose the subscribers telephone set in circuit with said cap telephone,substantially as de' scribed.

3. The combination with two metallic circuit telephone lines extendingto the central station and normally open at the subscribers station, ofa local metallic circuit containing an operators cap telephone normallyin circuit with the line of the calling subscriber, but cut therefrom bythe act of making connection at the central station, means at thesubscribers station for closing his telephone set in circuit with saidcap telephone, a double stranded cord connector looping the twotelephone lines together at the central station, a clearing outindicator in circuit at the central station, a battery in a bridgebetween the two strands of the cord connector, and means at thesubscribers stations for maintaining said battery circuit open or closedto cause said clearing out indicator to display the desired signal,substantially as described.

111 testimony that we claim the foregoing we have hereunto set our handsand seals.

JOHN I. SABIN. [L. 3.]

WILLIAM HAMPTON. LL. s] Witnesses:

EDWARD E. OSBORN, (3. W. M. SMITH.

